3D printing is a technology based on a digital model file that uses a powder or granular material to construct objects by layer-by-layer printing. 3D printing is usually done using digital technology material printers, and is often used for manufacturing models in the mold manufacturing, industrial design and other fields.
Hernia repair mesh is mainly used in the repair of abdominal hernia. Abdominal wall hernia refers to the bulging of the organs or tissues within the abdominal cavity from the abdominal wall of the weak or defect area. Abdominal wall hernia includes inguinal hernia, umbilical hernia, hernia, incisional hernia and stoma hernia and so on, and the inguinal hernia is the most common. Because the abdominal wall hernia has a high incidence, so its treatment has now become an important social problem.
The placement of synthetic meshes into the body of a patient has become routine in the field of surgical practice. The most common use for mesh implants is the placement into the abdominal cavity for the repair of ventral and incisional hernias. Intraperitoneal onlay mesh technique is indicated in multiple defect hernias as well as for the treatment of large abdominal wall defects with loss of domain in obese patients. The implants are usually fixed by sutures, tacks or anchors. Complications found with Intraperitoneal onlay mesh technique are seroma formation, impaired functionality of the abdominal wall, chronic pain and adhesion formation. Chronic pain (continuous or intermittent pain) persisting for more than 3 months postoperatively is mainly caused by perforating fixation devices with a reported incidence of 5-15% in open and laparoscopic hernia repair operations. The new trends for hernia repair include mini-invasive techniques, in which the hernia defect is closed by a piece of non-absorbable mesh with minimal tension. The follow-up times thus far are short for such procedures, and it seems that recurrence rates of 1% or below could be expected. Also, the general recovery time has become shorter, and the patients are usually encouraged to begin their normal activities with no restrictions within a week after the operation.
The commercially available meshes used in hernia repair today are typically made of various plastics, which can subdivided in to permanent (non-absorbable) or absorbable mesh. The most commonly used piece of hernia repair mesh polyester, polypropylene mesh and expanded polytetrafluoroethylene mesh. Polypropylene and polyester woven mesh material can help the surrounding tissue ingrowth, to improve the organizational strength and tensile strength. Also due to the large mesh macrophages and leukocytes can access, eliminate network of bacteria, so this type of mesh has a good anti-inflammatory effects, once infected, do not have to remove the mesh; however, these two materials are mesh into the abdominal cavity and internal organs cannot contact you because of a large number of animal experiments and clinical observations found that both mesh with the organization if they can produce severe adhesions in the abdominal cavity, gastrointestinal obstruction or fistula. Expanded polytetrafluoroethylene mesh is a microporous material, easy formation of adhesions in contact with abdominal viscera. But fibroblasts and macrophages cannot enter the pores, so the firm repaired and resistance to infection nor polypropylene and polyester mesh and, in the event of infection must be removed in order to control the meshing material. Further, permanent surgical implants (metals, plastics, silicone, etc.) have been shown to cause side effects in many patients because of corrosion, wearing, migration, chronic inflammation and risk of infection. When the foreign material is placed near sensitive organs, the risks of these side effects can be severe to the patient's well being. In the case of hernia surgery, the plastic mesh will always become situated into close contact with the sensitive intra-abdominal organs.
Bioabsorbable meshes made of polyglycolic acid and its lactide copolymer are also known. Since the 1970's, these bioabsorbable materials have been used in surgery as sutures. No major harm to the tissues has been generally reported from use of polyglycolic acid and its lactide copolymer, and these materials also induce fibrogenesis and scar formation to some extent. Unfortunately, sutures and meshes manufactured of polyglycolic acid or its lactide copolymers (with around 10 mol-% of lactide units) tend to lose their strength within about 1 month after implantation, in which time the hernia site would not have enough time to heal and form scar tissue to resist pressure.
Different mesh concepts for adhesion prevention have been developed including coated meshes, developed for separation of peritoneal defects and used for the individual coating of meshes. Large pores and high flexibility increase mesh integration into the abdominal wall and provide good biomechanical function. Examples for coated meshes are Parietex Composite®, Sepramesh® and Proceed®. The idea of integrating mesh and antiadhesive layer in the implant is to separate implant and viscera until the mesh is covered by neomesothelium (after approximately 10 days) and in the following to reduce the foreign body reaction and adhesion formation triggered by the implant. However, using coated meshes may still trigger adverse reaction due to the use of mechanical fixation means such as sutures, tacks and anchors, which may extend from the implant. It is therefore a goal of the present application to provide improved means to prevent or minimize all causes of unwanted tissue adhesion to the implant or its fixtures.
Clinical and experimental studies have shown that lightweight, large-pore hernia meshes, which have been increasingly implanted in clinical routine, possess better biocompatibility as attested to in numerous experimental and pathological studies. Due to lower inflammatory reaction and scar formation, the dynamics of the abdominal wall is preserved with sufficient stability and shrinkage of the mesh surface is reduced. The ideal surgical repair biological material requirements are: implant material causes physical changes within the organization, without chemical activity, does not cause inflammation and foreign body reaction, non-carcinogenic, non-allergenic and highly sensitized, good biocompatibility, without disturbing the electrolyte balance. Certain properties of each mesh, including tensile strength, elasticity, porosity, and method of fabrication, may greatly influence the tissue reaction to the prosthetic.
Although the use of a hernia mesh has been regarded as a basic means in performing hernia repairs, the decisions about which techniques to use are not well defined, and instead the choice depends on tradition, context, and familiarity with the type of hernia. It is extremely important that surgeons understand the full range of physicomechanical properties of mesh materials, particularly the extent to which these properties affect the body's response to the implanted material.